My girlfriend and I have recently tried introducing anal play into our bedroom, starting with beads. She really loved the sensation of the beads inside her, but when I started using the strap-on and thrusting more vigorously into her, the beads kept slipping out of her ass and wouldn’t stay in. I’m not sure if it’s because there was too much lube or what, but we had to stop since they wouldn’t stay in. Any tips on how to keep the beads from slipping out all the time & during vaginal penetration?